Developing solutions are used to process color photographic materials such as color photographic films and papers to provide the desired color images. Such solutions generally contain developing agents, for example 4-amino-3-methyl-N-(.beta.-methanesulfonamidoethyl)aniline, as reducing agents to react with suitable color forming couplers to form the desired dyes. However, such developing agents are susceptible to oxidation by dissolved oxygen. An antioxidant is conventionally included in the developer solutions to preserve the oxidation state of the color developer and thereby maintain useful color developer activity.
Many classes of compounds have been employed as color developer solution antioxidants, including hydroxylamines, hydroxamic acids, oximes, nitroxy radicals, hydrazines, hydrazides, phenols, saccharides, various simple amines, polyamines, quaternary ammonium salts, .alpha.-hydroxy ketones, alcohols, diamides and disulfonamides. To be used in practice, however, antioxidants must be soluble in aqueous media, non-toxic to living organisms, low cost and non-silver halide developers. Further, it is desirable that antioxidants react slowly with oxygen and rapidly with oxidized color developer, but not so rapidly that color development is retarded. Yet another concern is that the antioxidant must not be able to promote bacterial growth.
All of these considerations greatly limit the number and classes of compounds that practically can be used as antioxidants or stabilizers in color developer solutions. The compounds most often used as antioxidants are hydroxylamines. They exhibit excellent characteristics by having a slow rate of aerial oxidation, being non-silver halide developers, and are relatively inexpensive to produce. There are considerable publications describing such compounds.
Unfortunately, many hydroxylamines have significant vapor pressure at room temperatures, and have a characteristic unpleasant odor.
Considerable work has been carried out to improve various features of hydroxylamines, including their water-solubility so that odors from the release of amines is minimized. Thus, various solubilizing groups, including hydroxyl, carboxyl and sulfonyl groups have been put on hydroxylamines through simple reactions to reduce the odor problem.
Using hydroxyl side groups as a water solubilizing moieties additionally improves the stability of hydroxylamines toward catalytic decomposition by lessening their ability to leach metal ions from metal equipment used in processing. The presence of trace metal ions in processing solutions is known to catalyze hydroxylamine decomposition through aerial oxidation (Moews et al, J. Inorg. Nucl. Chem., 11, 242, 1959).
Known procedures for preparing hydroxylamines having solubilizing groups, including hydroxyl groups, typically include one or more synthetic reaction steps and isolation of the product which is then added to color developer solutions. There is a need for a simplified way to provide odorless color developer antioxidants which is cost effective and which provides antioxidants at least as effective as compounds prepared using conventional means.